Engineering of TCRs requires stabilization of the receptor prior to engineering for higher affinity. Chapter 4 details the engineering of a high affinity TCR in its native state, without the need for stabilization, using a T cell display system. T cells bearing the newly isolated TCR bound pepMHC and were activated in the absence of co-receptor. This result demonstrates the feasibility of engineering full-length TCRs on the surface of T cells using a retroviral vector.